Field guided post exposure bake application for photoresist microbridge defects

ABSTRACT

Embodiments described herein generally relate to methods for mitigating patterning defects. More specifically, embodiments described herein relate to utilizing field guided post exposure bake processes to mitigate microbridge photoresist defects. An electric field may be applied to a substrate being processed during a post exposure bake process. Photoacid generated as a result of the exposure may be moved along a direction defined by the electric field. The movement of the photoacid may contact microbridge defects and facilitate the removal of the microbridge defects from the surface of a substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims benefit to U.S. patentapplication Ser. No. 14/677,552, filed Apr. 2, 2015, the entirety ofwhich in herein incorporated by reference.

BACKGROUND Field

The present disclosure generally relates to methods and apparatus forprocessing a substrate, and more specifically to methods and apparatusfor reducing photoresist microbridge defects.

Description of the Related Art

Integrated circuits have evolved into complex devices that can includemillions of components (e.g., transistors, capacitors, and resistors) ona single microchip. Photolithography is a process which may be utilizedto pattern or shape various material layers during fabrication of thechip. Generally, the process of photolithography involves depositing aphotoresist layer on a substrate, masking the substrate, and exposingthe photoresist layer to electromagnetic radiation. The photoresistlayer may be a chemically amplified photoresist and may include a resistresin and a photoacid generator. The photoacid generator, upon exposureto electromagnetic radiation, generates acid which alters the solubilityof the photoresist in a development process. Excess solvent utilized inthe development process and solvated resist may then be removed toreveal a patterned material layer suitable for subsequent fabricationprocesses.

During exposure of the photoresist, a photomask or reticle may be usedto selectively expose certain regions of the photoresist layer to form adesired pattern on the substrate. However, the photomask or reticleutilized to pattern the photoresist may be defective and result in apatterned photoresist which is undesirable. A defect in patterning ofthe photoresist may result in the undesirable pattern being transferredto other layers on the substrate during subsequent processingoperations. For example, as illustrated in FIG. 1 (prior art), asubstrate 100 includes a material layer 102, a patterned resist layer104, and exposed regions 106. A microbridge defect 108, which may resultfrom defects during photolithography, undesirably bridges the exposedarea 106 where no resist material should exist after exposure.Microbridge defects may result from mask defects or from defects in thephotoresist, such as compositional heterogeneity with regard to photoacid generator concentration in specific regions of the photoresist.Microbridge defects are increasingly troublesome as critical devicedimensions are continually shrinking. Additionally, microbridge defectsreduce production yields and contribute to increased processing costsand reduced efficiencies.

Thus, there is a need for improved methods and an apparatus for reducingpatterning defects in microelectronic devices.

SUMMARY

In one embodiment, a method of processing a substrate is provided. Themethod includes positioning a substrate having a photoresist materialdisposed thereon patterned with latent image lines in a processingchamber and heating the photoresist material. An electric field may beapplied to the photoresist material in a direction parallel to thelatent image lines and a photoacid distribution may be altered along thedirection parallel to the latent image lines.

In another embodiment, a method of processing a substrate is provided.The method includes disposing a photoresist layer comprising a photoacidgenerator on a substrate and exposing a first portion of the photoresistlayer unprotected by a photomask to electromagnetic radiation in alithographic exposure process. An electric field may be applied to altermovement of photoacid generated from the photoacid generator in adirection parallel with a plane defined by the substrate. The electricfield may be applied by a first alternating pair of positive andnegative voltage antennae and a second alternating pair of positive andnegative antennae.

In yet another embodiment, a method of processing a substrate isprovided. The method includes disposing a photoresist layer comprising aphotoacid generator on a substrate and exposing a first portion of thephotoresist layer unprotected by a photomask to electromagneticradiation in a lithographic exposure process to form one or more latentimage lines. The substrate having the photoresist material disposedthereon patterned with latent image lines may be positioned in aprocessing chamber and the substrate and photoresist layer may beheated. An electric field may be applied to alter movement of photoacidgenerated from the photoacid generator in a direction parallel to thelatent image lines. The applying an electric field includes charging afirst antenna disposed above the photoresist layer and a second antennadisposed below the photoresist layer with a first voltage. The applyingan electric field also includes charging a third antenna disposed abovethe photoresist layer and a fourth antenna disposed below thephotoresist layer with a second voltage. The first and second voltagesmay have opposite polarities and the photoacid distribution may bealtered along the direction parallel to the latent image lines.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 (prior art) illustrates a perspective view of a patternedphotoresist layer disposed on a substrate and a microbridge defect asconventionally known in the art.

FIG. 2 illustrates a schematic, cross-sectional view of an apparatus forapplying an electric field to a substrate on which a photoresist layeris disposed according to one embodiment described herein.

FIG. 3 illustrates a schematic, side view of antennas configured toapply an electric field to the photoresist layer of the substrateaccording to one embodiment described herein.

FIG. 4A illustrates a perspective view of the substrate depicting anacid distribution control of the photoresist layer during a postexposure bake process according to one embodiment described herein.

FIG. 4B illustrates a partial schematic top view of a photoresist layerof FIG. 4A including a portion of a first region and the second regionwith a microbridge defect after lithographic exposure according to oneembodiment described herein.

FIG. 4C illustrates a partial schematic top view of the photoresistlayer of FIG. 4B including a portion of the first region and the secondregion with the microbridge defect during the field guided post exposurebake process according to one embodiment described herein.

FIG. 4D illustrates a partial schematic top view of the photoresistlayer of FIG. 4C including a portion of the first region and the secondregion after the field guided post exposure bake process has removed themicrobridge defect according to one embodiment described herein.

FIG. 5 illustrates a flow diagram of a method for controlling aciddistribution of a photoresist layer during a post-exposure bake processaccording to one embodiment described herein.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the Figures. Additionally, elements of one embodiment may beadvantageously adapted for utilization in other embodiments describedherein.

DETAILED DESCRIPTION

Embodiments described herein generally relate to methods for mitigatingpatterning defects. More specifically, embodiments described hereinrelate to utilizing field guided post exposure bake processes tomitigate microbridge photoresist defects. An electric field may beapplied to a substrate being processed during a post exposure bakeprocess. Photoacid generated as a result of the exposure may be movedalong a direction defined by the electric field. The movement of thephotoacid may contact microbridge defects and facilitate the removal ofthe microbridge defects from the surface of a substrate.

Microbridge defects may result from a non-homogenous compositionalprofile of a photoresist or a photomask defect. Utilizing a photoacidgenerator during a post-exposure bake procedure in combination with anapplied electric field may mitigate the occurrence of microbridgedefects. Methods disclosed herein apply an electric field to a substrateon which the photoresist layer is disposed during a post-exposure bakeoperation of a photolithography processes. Application of the electricfield as described herein controls the diffusion and distribution of theacids generated by the photoacid generator, reducing or preventing themicrobridge defects as a result of selectively positioning the acids tosolvate portions of the resist which exist as microbridge defects.Apparatuses and methods for performing the above-mentioned techniquesare disclosed herein.

FIG. 2 illustrates a schematic side view of one embodiment of aprocessing chamber 200 in which a post-exposure bake procedure may beperformed with an electric field applied to a substrate 240 inaccordance with one embodiment described herein. As described above, thepost-exposure bake procedure is performed after an exposure operation ofa photolithography process, in which a photoresist layer 250 on thesubstrate 240 is exposed to electromagnetic radiation. The photoresistlayer 250 may be formed on the substrate 240 and may include a resistresin and a photoacid generator. A mask or other mechanism is used toselectively expose the photoresist layer 250 to electromagneticradiation. Exposure of portions of the photoresist layer 250 throughopenings in the mask causes a latent pattern to form in the photoresistlayer 250, where the layout of the latent pattern is dependent on thelayout of the mask. The latent pattern is characterized by a change inthe chemical properties of the photoresist layer 250 such thatsubsequent processing can selectively remove desired portions of thephotoresist layer 250. For example, the photoacid generated as a resultof the exposure may function to solvate the photoresist layer 250 whichmay be removed during a subsequent photoresist removal process.

The post-exposure bake process may be performed after the exposureoperation may include the application of heat to the photoresist layer250. The application of heat may cause further changes to the chemicalproperties of the photoresist layer 250 such that a subsequentdevelopment operation will selectively remove the portions of thephotoresist. The techniques disclosed herein include applying anelectric field having a specified configuration during the post-exposurebake process such that a subsequent development operation will removeportions of the photoresist in a manner such that microbridge defectsare reduced or eliminated.

The substrate 240 on which the photoresist layer 250 is disposed may beany suitable type of substrate, such as a dielectric substrate, a glasssubstrate, a semiconductor substrate, a conductive substrate, or thelike. The substrate 240 may have a material layer 245 disposed thereonany may be any desired layer, such as a semiconducting material, or anoxide material, among others. In other embodiments, the substrate 240may have more than one material layer 245. The substrate 240 may alsohave the photoresist layer 250 disposed over the material layer 245.When the post-exposure bake process is performed, the substrate 240 hasbeen previously exposed to electromagnetic radiation in an exposureoperation of a photolithography process. As a result, the photoresistlayer 250 has latent image lines 255 which define a latent image of theelectromagnetically-altered photoresist. The latent image lines 255 maybe in a desirable pattern, for example, the latent image lines 255 maybe substantially parallel to each other. In other embodiments, thelatent image lines 255 may not be substantially parallel to each other.

The processing chamber 200 includes a substrate support assembly 238.The substrate support assembly 238 includes a substrate automationsystem 215 with a belt 213. The belt 213 may be moved via one or morerollers 212 which support and move the substrate 240. The processingchamber 200 may receive a linear array of substrates 240 through one ormore apertures 203 formed in the sides of the processing chamber 200.The processing chamber 200 includes one or more electrode assemblies 216configured to provide an electric field to the substrates 240 during thepost-exposure bake process. The processing chamber 200 also includes aheating mechanism (discussed below) to apply heat to the substrate 240while the electric field is applied for the post-exposure bake process.

The electrode assembly 216 includes at least a first electrode 258 and asecond electrode 260. In some embodiments, the electrode assembly 216may be coupled to one or more walls 202 by a fixed stem (not shown). Asshown, the first electrode 258 is coupled to a power source 270, and thesecond electrode 260 is coupled to a power supply 275. Electrodeassemblies 216 may be provided both above the belt 213 and below thebelt 213 (and thus both above and below substrates 240 disposed on thebelt) to provide a desired electric field configuration.

The substrate 240 may also be positioned in such a manner on the belt213 such that the substrate is electrically floating. Thus, thesubstrate 240 is not electrically coupled to any conductive elements ofthe processing chamber 200 or to ground. The processing chamber 200 mayinclude one or more features to electrically float the substrate 240. Inone example, the belt 213 may have an electrically insulating materialdisposed on a top surface of the belt 213. In this example, thesubstrate 240 may be placed on the electrically insulating material onthe belt 213 in order to electrically float the substrate 240 within thechamber 200. In another example, the substrate 240 may be disposed onthe belt, which is electrically isolated from other components of theprocessing chamber 200. In yet another example, the processing chamber200 includes an electrically floating arm or other apparatus upon whichthe substrate 240 is disposed. Electrically floating the substrate 240influences the shape of the electrical field applied by the electrodeassembly 216 into a desired configuration. More specifically,electrically floating the substrate 240 may influence electric fieldline shape and cause the electric field lines to remain substantiallyparallel to the top (and/or bottom) surface of the substrate 240, whichis generally parallel to the surface of the belt 213.

The processing chamber 200 may also include one or more heat sources 280to provide heat to the photoresist layer 250 during the post-exposurebake process. One example of the heat source 280, as illustrated in FIG.2, includes one or more heat lamps positioned within or outside theprocessing chamber 200. In another example of a heat source, one or morelasers may be used to heat the photoresist layer 250 (or other layer)positioned on the substrate 240. In a further example of a heat source,the supply source 204 may be configured to provide heated gas to theprocessing chamber 200 in order to heat the photoresist layer 250. Inyet another example of a heat source, a microwave heater may be used toheat the photoresist layer 250. In still another example of the heatingmechanism, instead of using a belt 213, the substrate 240 may instead besupported by an arm that is heated and thus conductively transfers thatheat to the photoresist layer 250. In such embodiments, the arm may beelectrically floating or a surface of the arm that supports thesubstrate 240 may include an electrically insulating layer to cause thesubstrate 240 to be electrically floating.

The configuration of the electrode assemblies 216 and the electricalfloating of the substrate 240 define a desired electric fieldconfiguration. More specifically, the electrode assembly 216 isconfigured to generate an electric field parallel to the x-y planedefined by the surface of the belt 213. The electrical floating of thesubstrate 240, among other variables, causes the electric field to besubstantially parallel to the surface of the substrate 240 along asubstantially large portion of the substrate 240. Moving the substrate240 via the belt 213 through the processing chamber while the electricfield and heat are applied may cause the charged species to move in adesired direction to solvate any photoresist present on the substrate240 as a microbridge defect. The charged species may be the acidsdescribed above that are present in the photoresist layer. These acidsmay be charged, and thus an electric field may affect motion of thecharged species.

When applying the electric field and heating the substrate 240, theprocessing chamber 200 may be filled with a non-reactive gas. Theprocessing chamber 200 may also be under vacuum generated by a vacuumpump 242 during the post-exposure bake process. The processing chamber200 may be enclosed by a plurality of walls 202. The walls 202 aregenerally formed from a material suitable for structurally supportingthe loads applied by the external environment, such as aluminum,stainless steel, or alloys and combinations thereof.

The apertures 203 may be sealed with a sealing mechanism, such as a slitvalve, when the post-exposure bake process is performed to allow avacuum to be generated in the interior of the processing chamber 200. Avacuum port 214 may be present in any one of the walls 202 to allow avacuum pump 242 to generate vacuum via valve 219. The vacuum pump 242may reduce the pressure within the processing chamber 200 and exhaustany gases and/or process by-products out of the processing chamber 200.Gas inlets 217 allow a supply source 204 to provide gases to theinterior of the processing chamber 200.

In the example illustrated in FIG. 2, the substrate automation system215 includes a conveyor 221 that is adapted to support and guidesubstrates 240 through the processing chamber 200 by use of one or moreactuators (not shown), for example, a stepper motor or servo motor. Inone configuration, the conveyor 221 comprises two or more rollers 212and a belt 213 that are configured to support and move the substrates240 through the processing chamber 200. In various embodiments, theprocessing chamber 200 may comprise other types of processing chambers.For example, instead of a processing chamber with conveyor belt, theprocessing chamber 200 may be a single substrate processing chamber or abatch processing chamber. The processing chamber 200 may also be part ofa processing system, such as an in-line processing system, a clusterprocessing system, or the track processing system as desired.

The power source 270 and the power supply 275 may have variouscharacteristics in order to provide the electric field described above.For example, the power source 270 and the power supply 275 may beconfigured to supply between about 500 V and about 100 kV to theelectrode assembly 216. An electric field may be generated having astrength between about 0.1 MV/m and about 100 MV/m. In one embodiment,the field strength may be between about 1 MV/meter and about 5 MV/meter,such as about 2 MV/meter. In some embodiments, either or both of thepower source 270 or the power supply 275 are a pulsed direct current(DC) power supply. The pulsed DC wave may be from a half-wave rectifieror a full-wave rectifier. The DC power may have a frequency of betweenabout 0 Hz and 1 MHz. The duty cycle of the pulsed DC power may be frombetween about 5% and about 95%, such as between about 20% and about 60%.In some embodiments, the duty cycle of the pulsed DC power may bebetween about 20% and about 40%. In other embodiments, the duty cycle ofthe pulsed DC power may be about 60%. The rise and fall time of thepulsed DC power may be between about 1 ns and about 1000 ns, such asbetween about 10 ns and about 500 ns. In other embodiments, the rise andfall time of the pulsed DC power may be between about 10 ns and about100 ns. In some embodiments, the rise and fall time of the pulsed DCpower may be about 500 ns.

In some embodiments, either or both of the power source 270 and thepower supply 275 are an alternating current power supply. The waveformapplied by such an alternating current power supply may be a sinusoidalwaveform. The frequency of such a sinusoidal waveform may be frombetween 1 Hz to 1 KHz, although the frequency is not limited to thosenumbers. This AC waveform may be combined with a pulse, as well. Inother embodiments, either or both of the power source 270 and the powersupply 275 are a direct current power supply. In some embodiments,either or both of the power source 270 and the power supply 275 may usea DC offset. The DC offset may be, for example, between about 0% andabout 75% of the applied voltage, such as between about 5% and about 60%of the applied voltage.

FIG. 3 illustrates a schematic side view of pairs of antennas 320, 321above and below a substrate 240 that includes a photoresist layer 250(shown in FIG. 2). The electrode assembly 216 (also shown in FIG. 2),which is positioned above and below substrate 240, includes the antennas320, 321. The antennas 320, 321 are configured to provide an electricfield within the processing chamber 200 influence the position ofphotoacid generated by the photoresist layer 250 after an exposureoperation. FIG. 3 shows an exemplary configuration of the electric fieldthat is produced by the antennas 320, 321.

As illustrated, an antenna 320(1) having a positive voltage is disposedabove the substrate 240 and an antenna 320(2) having substantially thesame voltage as the antenna 320(1) is disposed below the substrate.Antenna 320(1) is spaced apart from antenna 320(2) by distance d₁. Also,an antenna 321(1) is disposed above the substrate 240 and is spacedapart from antenna 320(1) by distance d₂. Antenna 321(2) is disposedbelow the substrate 240 and is spaced apart from antenna 321(1) by d₁and from antenna 320(2) by d₂. Antenna 321(1) and antenna 321(2) have anegative voltage as compared with antenna 320(1) and 320(2). Antenna321(1) and antenna 321(2) have substantially the same voltage. Thisconfiguration, in which two vertically aligned “positive” antennas andtwo vertically aligned “negative” antennas are disposed above and belowthe substrate 240, forms an electric field with desirablecharacteristics parallel to the surface of the photoresist 250.

When the substrate 240, with photoresist 250, is heated in the presenceof an electric field generated by the antennas 320, 321 disposed bothabove and below the substrate 240, a uniformity of directional movementis applied to charged species (i.e., protons of the photoacid). Theuniform directional movement of the charged species is shown by thedouble headed arrow 330.

For clarity, only two pairs of antennas 320, 321 are shown. However, itis contemplated that additional antennas may be present in theprocessing chamber as well. For example, antennas 320, 321 in ahorizontal alignment or stacked vertical alignment may also be utilizedto form a suitable electric field.

In operation, a voltage may be supplied from a power supply, such as thepower source 270 and/or the power supply 275, to the first terminal 310and/or the second terminal 311. The supplied voltage creates an electricfield between each antenna of the one or more antennas 320 and eachantenna of the one or more antennas 321. The electric field willgenerally be strongest between an antenna of the one or more antennas320 and an adjacent antenna of the one or more antennas 321. Theantennas 320, 321 may be interleaved and aligned in a spatialrelationship configured to produce an electric field predominantly in adirection parallel to the plane defined by the surface of the belt 213(i.e., the X-Y plane).

The substrate 240 is positioned on the belt 213 such that the latentimage lines 255 are parallel to the electric field lines generated bythe electrode assembly 216. As a result of the protons generated by thephotoacid, the charged species may be influenced by the electric field.As such, the electric field drives the charged species generated by thephotoacid in the photoresist layer 250 in the direction of the electricfield. By driving the charged species in a direction parallel with thelatent image lines 255, any existing microbridge defect may be exposedto and contacted the charged species to solvate the photoresistcomprising the microbridge defect. In contrast, when a voltage is notapplied to the first terminal 310 and/or the second terminal 311, anelectric field is not created to drive the charged species in anyparticular direction. As a result, the charged species may moverandomly, which provides no controlled microbridge defect removal andmay also undesirably result in increased line edge roughness.

FIG. 4A illustrates a photoresist layer 404 disposed on a material layer402 formed on a substrate 400 during a lithography exposure process. Asdiscussed above, an electric field from the electrode assembly 216 isapplied during a post exposure baking process. During the lithographicexposure process, radiation 412 is directed to a first region 408 of thephotoresist layer 404 while with a second region 406 of the photoresistlayer 404 protected by a photomask 410. Photoacid, depicted as e⁻ inFIG. 4A, is generated in the exposed first region 408 in the photoresistlayer 404 when the photoacid generator (PAG) is exposed to the radiation412, such as ultraviolet (UV) radiation. A microbridge defect 440 isillustrated as remaining in the first region 408, which may be a resultof a non-homogenous distribution of PAG in the photoresist layer 404 ormay be the result of a defect in the photomask 410. Although FIG. 4Aillustrates the photoacid with an “e⁻” symbol, it is not specificallyintended to be reflective of the actual charge of photoacid compounds,rather, it is representative of the fact that photoacid compoundsgenerally are electrically charged.

More specifically, the photoacid generator generates charged species,such as an acid cation and an anion. The photoacid generator may alsogenerate polarized species. Representative photoacid generators includesulfonate compounds, such as, for example, sulfonated salts, sulfonatedesters, and sulfonyloxy ketones. Other suitable photoacid generatorsinclude onium salts, such as aryl-diazonium salts, halonium salts,aromatic sulfonium salts and sulfoxonium salts or selenium salts. Otherrepresentative photoacid generators include nitrobenzyl esters,s-triazine derivatives, ionic iodonium sulfonates,perfluoroalkanesulfonates, aryl triflates and derivatives and analogsthereof, pyrogallol derivatives, and alkyl disulfones. Other photoacidgenerators may also be used.

In a conventional process, photoacid is primarily generated in theexposed first region 408 of the photoresist layer 404 during thelithographic exposure process. During the post-exposure bake period,movement of photoacid is generally random and the interface betweenareas within the photoresist layer 404 that include the generatedphotoacid and areas that do not include the generated photoacid maycomprise an unclear boundary (i.e., interface 430). For example, therandom movement may result in at least a portion of the photoaciddiffusing into the second region 406, as shown in the arrow 422. Suchphotoacid drift may result in line edge roughness, resolution loss,photoresist footing, and profile deformation, which may cause inaccuratetransfer of features to the underlying material layer 402. Moreover,mitigation of microbridge defects cannot be adequately addressed withrandom movement of the photoacid. As a result, inaccurate transfer offeatures could lead to device failure.

By applying the electric field described above to the photoresist layer404 during the post-exposure bake process, distribution of photoacid inthe exposed first region 408 may be efficiently controlled and confined.The electric field as applied to the photoresist layer 404 may movephotoacid in a direction parallel to the latent image lines (e.g., they-direction shown by arrow 414, which is substantially parallel to theplanar surface of the substrate 400) with minimal lateral motion (e.g.,x direction shown by the arrow 422). As such, the photoacid generallydoes not diffuse into the adjacent second region 406. Generally,photoacid has a certain polarity that may be affected by an electricfield applied thereto. Such an applied electric field will orientphotoacid molecules in directions that are in accordance with theelectric field. When such electric field is applied, the photoacid movesin a desired direction such that the photoacid may contact and solvatemicrobridge defects 440 which are disposed within an area along thefield direction.

FIG. 4B illustrates a partial schematic top view of the photoresistlayer 404 of FIG. 4A including a portion of the first region 408 and thesecond region 406 with the microbridge defect 440 after lithographicexposure. The microbridge defect 440, as described above, may be presentas a result of a photomask defect or non-homogenous distribution of PAGwithin the photoresist. This is illustrated as photoacid (e) present inthe first region 408, but not present where the microbridge defect 440exists.

FIG. 4C illustrates a partial schematic top view of the photoresistlayer 404 of FIG. 4B including a portion of the first region 408 and thesecond region 406 with the microbridge defect 440 during the fieldguided post exposure bake process. During the field guided post exposurebake process, the electric field in applied in a desired direction, forexample, parallel to the latent image lines illustrated. The directionof the field is illustrated by arrow 414. Accordingly, the photoacid ismoved along the direction of the field such that the photoacid is movedinto contact with the microbridge defect 440. The field guided postexposure bake process may be performed for an amount of time suitable tosolvate and/or remove the microbridge defect 440.

FIG. 4D illustrates a partial schematic top view of the photoresistlayer 404 of FIG. 4C including a portion of the first region 408 and thesecond region 406 after the field guided post exposure bake process hasremoved the microbridge defect 440. As illustrated, the microbridgedefect 440 has been removed as a result of the controlled migration andmovement of the photoacid which is now present where the microbridgedefect 440 once existed.

FIG. 5 illustrates a flow diagram of a method 500 for controllingphotoacid distribution/diffusion in a photoresist layer during alithographic exposure process or during a prebaking process or apost-baking process. The method 500 begins at operation 510 bydetermining an orientation of latent image lines formed in a photoresistlayer disposed on a substrate. In one embodiment, the latent image linesmay be substantially parallel and the orientation of the lines on thesubstrate may be determined by various suitable methods. In certainembodiments, the determining the orientation of the latent image linesmay be optional.

At operation 520, the substrate may be positioned in a suitableprocessing chamber. Generally, the processing chamber, such as theprocessing chamber 200 described in FIG. 2, may have a plurality ofantennas configured to generate an electric field. In one embodiment,the substrate may be positioned within the processing chamber such thatthe orientation of the latent image lines is parallel with the electricfield generated by the antennas.

At operation 530, an electric field may be applied to the photoresist.Prior to, during, or subsequent to the application of the electricfield, the substrate may be heated to a suitable temperature tofacilitate photoacid movement. For example, the photoresist may bemaintained at a temperature between about 10° C. and about 160° C., suchas between about 30° C. and 140° C. In one embodiment, the electricfield is applied during a baking process and the electric field isapplied parallel to latent image line formed on the photoresist.

At operation 540, an acid distribution within the photoresist may bealtered. The alteration or movement and migration of photoacid withinthe resist is controlled by the application of the electric fielddescribed with regard to operation 530. The electric field may beapplied to the photoresist for an amount of time suitable to remove anymicrobridge defects present on the substrate. For example, the electricfield may be applied between about 30 seconds and about 120 seconds. Itis also contemplated that the electric field may be applied even if nomicrobridge defects exist to improve line edge roughness for subsequentpattern image transfer.

In addition, the photoresist may optionally be developed. In oneembodiment, after the completion of operation 540, the substrate 140 maybe transferred to a development chamber. The photoresist may bedeveloped by, for example, exposing the photoresist to a developer, suchas a sodium hydroxide solution, a tetramethylammonium hydroxidesolution, xylene, or Stoddard solvent. The substrate may be rinsed with,for example, water or n-butylacetate.

Additional post-processing steps may also be performed. The additionalpost-processing steps may be performed, for example, in apost-processing chamber. For example, after rinsing, the substrate maybe hard baked and inspected. After inspection, an etching process may beperformed on the substrate. The etching process may generally utilizethe features of photoresist, such as the latent image lines to transfera pattern to the substrate.

Although described above in the context of mitigating microbridgedefects and line edge roughness, the techniques provided above mayadditionally be used to improve the sensitivity of photoresist. Thissensitivity is associated with the reaction that makes the photoresistsoluble. By applying the electromagnetic field techniques describedabove, the reaction that causes the photoresist to become soluble issped up, which improves the sensitivity.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A substrate processing apparatus, comprising: achamber having a plurality of walls defining a process volume; a supportassembly disposed within the process volume, the support assemblycomprising: a belt; and one or more rollers; a first electrode assemblycomprising a first electrode and a second electrode positioned adjacenta first side of the belt; and a second electrode assembly comprising afirst electrode and a second electrode positioned adjacent a second sideof the belt opposite the first side of the belt, wherein the firstelectrode of the first electrode assembly and the first electrode of thesecond electrode assembly are configured to be powered by a first powersupply, and wherein the second electrode of the first electrode assemblyand the second electrode of the second electrode assembly are configuredto be powered by a second power supply.
 2. The apparatus of claim 1,wherein the walls are formed from a material selected from the groupconsisting of aluminum, stainless steel, alloys thereof, andcombinations thereof.
 3. The apparatus of claim 1, wherein one or moreapertures are formed in the plurality of walls.
 4. The apparatus ofclaim 3, wherein the one or more apertures are configured to be sealedby a slit valve.
 5. The apparatus of claim 1, wherein an electricallyinsulating material is disposed on the belt.
 6. The apparatus of claim1, wherein the belt is electrically isolated from conductive componentsof the chamber.
 7. The apparatus of claim 1, further comprising: one ormore heat sources.
 8. The apparatus of claim 7, wherein the heat sourcesare selected from the group consisting of heat lamps, lasers, heatedgas, and microwave heaters.
 9. The apparatus of claim 1, wherein thefirst electrode and the second electrode of the first electrode assemblyare interleaved.
 10. The apparatus of claim 9, wherein the firstelectrode and the second electrode of the second electrode assembly areinterleaved.
 11. The apparatus of claim 1, wherein the first powersupply and the second power supply are an alternating current powersupply.
 12. The apparatus of claim 1, wherein the first power supply andthe second power supply are a direct current power supply.
 13. Theapparatus of claim 1, wherein the first power supply is an alternatingcurrent power supply and the second power supply is a direct currentpower supply.
 14. The apparatus of claim 1, wherein the first powersupply and the second power supply are configured to supply betweenabout 500V and about 100 kV to respective electrodes of the firstelectrode assembly and the second electrode assembly.
 15. A substrateprocessing apparatus, comprising: a chamber having a plurality of wallsdefining a process volume; a conveyor comprising a belt disposed withinthe process volume; a first electrode assembly comprising a firstelectrode interleaved with a second electrode, the first electrodeassembly positioned adjacent a first side of the belt; and a secondelectrode assembly comprising a first electrode interleaved with asecond electrode, the second electrode assembly positioned adjacent asecond side of the belt opposite the first side of the belt, wherein thefirst electrode of the first electrode assembly and the first electrodeof the second electrode assembly are configured to be powered by a firstpower supply, and wherein the second electrode of the first electrodeassembly and the second electrode of the second electrode assembly areconfigured to be powered by a second power supply.
 16. The apparatus ofclaim 15, wherein the first electrode assembly is disposed above thebelt.
 17. The apparatus of claim 16, wherein the second electrodeassembly is disposed below the belt.
 18. The apparatus of claim 15,wherein each of the first electrode and the second electrode of thefirst electrode assembly and each of the first electrode and the secondelectrode of the second electrode assembly are coupled one or more ofthe plurality of walls by a fixed stem.
 19. A substrate processingapparatus, comprising: a chamber having a plurality of walls defining aprocess volume; a conveyor comprising a belt disposed within the processvolume; a first electrode assembly comprising a first electrodeinterleaved with a second electrode, the first electrode assemblypositioned adjacent a first side of the belt; and a second electrodeassembly comprising a first electrode interleaved with a secondelectrode, the second electrode assembly positioned adjacent a secondside of the belt opposite the first side of the belt, wherein the firstpower supply coupled to the first electrode of the first electrodeassembly and the first electrode of the second electrode assembly areconfigured to be powered by a first power supply with a voltage having afirst polarity, and the second power supply coupled to the secondelectrode of the first electrode assembly and the second electrode ofthe second electrode assembly are configured to be powered by a secondpower supply with a voltage having a second polarity different form thefirst polarity.
 20. The apparatus of claim 19, wherein both of the firstpower supply and the second power supply are pulsed direct current powersupplies.